U.S. patent application number 14/737495 was filed with the patent office on 2016-08-18 for dithiocarbamate functionalized dendrimer with alkylenediamine core as soil heavy metal immobilization amendment and preparation method thereof.
The applicant listed for this patent is Tongji University. Invention is credited to Fengting Li, Haiyan Tian, Bingru Zhang, Huangpu Zhao, Weixiao Zhou.
Application Number | 20160237029 14/737495 |
Document ID | / |
Family ID | 53308087 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160237029 |
Kind Code |
A1 |
Zhang; Bingru ; et
al. |
August 18, 2016 |
Dithiocarbamate functionalized dendrimer with alkylenediamine core
as soil heavy metal immobilization amendment and preparation method
thereof
Abstract
A dithiocarbamate functionalized dendrimer with an
alkylenediamine core, a dithiocarbamate pendant functional group
and a dithiocarbamate end functional group, as a soil heavy metal
immobilization amendment, and a preparation method thereof are
provided. The dithiocarbamate functionalized dendrimer has a
chemical formula of
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2CH.sub.2N(CSSM)CH.sub.2(CH.sub.2).sub.bCH.sub.2N(CSS
M).sub.2).sub.2].sub.2}.sub.2, wherein a is a positive integer
larger than 2; b is a positive integer at a range of 0-4; and M is
Na.sup.+, NH.sub.4.sup.+ or K.sup.+. The dithiocarbamate
functionalized dendrimer with the alkylenediamine core is used for
an in-suit immobilization remediation for soil contaminated by
heavy metals, and has advantages of a small dosage, high
efficiency, safety and rapidness. The dendrimer is able to
effectively immobilize exchangeable and carbonated bound forms of
the heavy metals, in such a manner that the immobilized heavy
metals are able to resist an influence from natural environment for
a long term, such as an acid rain.
Inventors: |
Zhang; Bingru; (Shanghai,
CN) ; Li; Fengting; (Shanghai, CN) ; Zhao;
Huangpu; (Shanghai, CN) ; Zhou; Weixiao;
(Shanghai, CN) ; Tian; Haiyan; (Shanghai,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tongji University |
Shanghai |
|
CN |
|
|
Family ID: |
53308087 |
Appl. No.: |
14/737495 |
Filed: |
June 12, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C 333/26 20130101;
B09C 1/08 20130101; B09C 2101/00 20130101 |
International
Class: |
C07C 333/16 20060101
C07C333/16; B09C 1/08 20060101 B09C001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2015 |
CN |
201510072596.0 |
Claims
1. A dithiocarbamate functionalized dendrimer with an
alkylenediamine core as a soil heavy metal immobilization
amendment, wherein: the dithiocarbamate functionalized dendrimer
with the alkylenediamine core has a chemical formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2CH.sub.2N(CSSM)CH.sub.2(CH.sub.2).sub.bCH.sub.2N(CSSM).sub.2).su-
b.2].sub.2}.sub.2; and the dithiocarbamate functionalized with the
alkylenediamine core has a chemical formula of: ##STR00007##
wherein a is a positive integer larger than 2, b is a positive
integer at a range of 0-4, and M is Na.sup.+, NH.sub.4.sup.+ or
K.sup.+.
2. A method for preparing the dithiocarbamate functionalized
dendrimer with the alkylenediamine core as the soil heavy metal
immobilization amendment as recited in claim 1, comprising steps
of: (1) preparing a double bond-terminated lower generation
dendrimer with an alkylenediamine core, comprising steps of: adding
a methanol solution of trimethylolpropane triacrylate into a first
round-bottom flask with a first stirrer, a first reflux condenser
and a first thermometer; then dropping an alcohol solution of the
alkylenediamine by two to five times into the first round-bottom
flask to form a first mixture, at a temperature of lower than
10.degree. C., under a nitrogen protection and a stirring
condition; controlling a dropping speed to keep the temperature
lower than 10.degree. C. when dropping; reacting, by the first
mixture, for 8-16 h at a temperature of 25.degree. C. after each
dropping; after a reaction of the first mixture is finished,
dissolving out a pale amber product; filtering out the pale amber
product, washing the pale amber product with methanol, and drying
the pale amber product in a vacuum at a temperature of 40.degree.
C., so as to obtain a pale amber double bond-terminated lower
generation dendrimer with the alkylenediamine core; wherein the
double bond-terminated lower generation dendrimer with the
alkylenediamine core has a chemical formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2.dbd.CH.sub.2).sub.2].sub.2}.sub.2; and wherein a
reaction equation of the step (1) is:
4C.sub.2H.sub.5C(CH.sub.2OCOCH.dbd.CH.sub.2).sub.3+H.sub.2N(CH.sub.2).sub-
.aNH.sub.2.fwdarw.(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H-
.sub.5)(CH.sub.2OCOCH.sub.2.dbd.CH.sub.2).sub.2].sub.2}.sub.2,
wherein a is the positive integer larger than 2; (2) preparing an
amine-terminated higher generation dendrimer with an
alkylenediamine core, comprising steps of: adding a methanol
solution of the alkylenediamine into a second round-bottom flask
with a second stirrer, a second reflux condenser and a second
thermometer; adding the methanol solution of the double
bond-terminated lower generation dendrimer with the alkylenediamine
core obtained by the step (1) into the second round-bottom flask,
to form a second mixture, at the temperature of lower than
10.degree. C., under the nitrogen protection and the stirring
condition; uniformly stirring the second mixture; reacting, by the
second mixture, for 20-30 h at the temperature of 25.degree. C.;
distilling the second mixture under a reduced pressure for 3-5 h at
a temperature of 80-100.degree. C. to remove methanol and redundant
alkylenediamine, so as to obtain a pale amber viscous product which
is the amine-terminated higher generation dendrimer with the
alkylenediamine core; wherein the amine-terminated higher
generation dendrimer with the alkylenediamine core has a chemical
formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2CH.sub.2NHCH.sub.2(CH.sub.2).sub.bCH.sub.2NH.sub.2).sub.2].sub.2-
}.sub.2; and wherein a reaction equation of the step (2) is:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2.dbd.CH.sub.2).sub.2].sub.2}.sub.2+8H.sub.2NCH.sub.2(CH.sub.2).s-
ub.bCH.sub.2NH.sub.2.fwdarw.(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2-
C(C.sub.2H.sub.5)(CH.sub.2OCOCH.sub.2CH.sub.2NHCH.sub.2(CH.sub.2).sub.bCH.-
sub.2NH.sub.2).sub.2].sub.2}.sub.2, wherein a is the positive
integer larger than 2 and b is the positive integer at the range of
0-4; and (3) preparing a dithiocarbamate functionalized dendrimer
with an alkylenediamine core, comprising steps of: adding the
amine-terminated higher generation dendrimer with the
alkylenediamine core obtained by the step (2) into a third
round-bottom flask with a third stirrer, a third reflux condenser
and a third thermometer; decreasing the temperature to be lower
than 10.degree. C. and introducing nitrogen; dropping an alkali
solution slowly at the temperature of lower than 10.degree. C. into
the third round-bottom flask, and then dropping an ethanol solution
of carbon disulfide slowly at the temperature of lower than
10.degree. C. into the third round-bottom flask, so as to form a
third mixture; after the dropping is finished, reacting by the
third mixture for 2-5 h at a temperature of 5-10.degree. C.;
increasing the temperature to 25.degree. C. and then reacting, by
the third mixture, for 3-5 h; storing the third mixture, as an
aqueous reaction mixture, overnight to dissolve out white
precipitate; filtering out the precipitate and washing the
precipitate with a small amount of ethanol; and then filtering out
the precipitate again to obtain a target product: a dithiocarbamate
functionalized dendrimer with the alkylenediamine core; wherein the
dithiocarbamate functionalized dendrimer with the alkylenediamine
core has a chemical formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2CH.sub.2N(CSSM)CH.sub.2(CH.sub.2).sub.bCH.sub.2N(CSSM).sub.2).su-
b.2].sub.2}.sub.2; and wherein a reaction equation of the step (3)
is:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2O-
COCH.sub.2CH.sub.2NHCH.sub.2(CH.sub.2).sub.bCH.sub.2NH.sub.2).sub.2].sub.2-
}.sub.2+24CS.sub.2+24MOH.fwdarw.(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.s-
ub.2C(C.sub.2H.sub.5)(CH.sub.2OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2(CH.sub.2)-
.sub.bCH.sub.2N(CSSM).sub.2).sub.2].sub.2}.sub.2+24H.sub.2O,
wherein a is the positive integer larger than 2, b is the positive
integer at the range of 0-4, and M is Na.sup.+, NH.sub.4.sup.+ or
K.sup.+; and wherein: in the step (1), a mole ratio of the
trimethylolpropane triacrylate to the alkylenediamine is
4.1:1-4.9:1; in the step (2), a mole ratio of the double
bond-terminated lower generation dendrimer to the alkylenediamine
is 1:15-1:20; and in the step (3), a mole ratio among the
amine-terminated higher generation dendrimer, the carbon disulfide
and the alkali is 1:(30-36):(30-36).
3. A method for in-suit immobilizing and remedying soil
contaminated by heavy metals with the dithiocarbamate
functionalized dendrimer with the alkylenediamine core as recited
in claim 1, comprising steps of: preparing the dithiocarbamate
functionalized dendrimer with the alkylenediamine core into a
solution; uniformly mixing the solution with the soil contaminated
by the heavy metals, wherein an addition dosage of the solution is
0.5%-5% of a weight of the soil; and storing the mixed soil for at
least one day, so as to realize an in-situ immobilization for the
soil contaminated by the heavy metals, and to resist an influence
from natural environment for a long term.
Description
CROSS REFERENCE OF RELATED APPLICATION
[0001] The present invention claims priority under 35 U.S.C.
119(a-d) to CN 201510072596.0, filed Feb. 12, 2015.
BACKGROUND OF THE PRESENT INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to a technical field of
environmental protection, especially belongs to a technical field
of soil contamination treatment, and more particularly to a
dithiocarbamate functionalized dendrimer with an alkylenediamine
core as a soil heavy metal immobilization amendment and a
preparation method thereof.
[0004] 2. Description of Related Arts
[0005] Along with the continuous expansion of the industrial
production scale and the rapid development of the urbanization in
China, the soil is suffering from various degrees of heavy metal
contaminations. The soil heavy metal contamination mainly comes
from the human activities, such as mining, smelting,
electroplating, tanning and metal processing.
[0006] The Report on the national general survey of soil
contamination, firstly published on Apr. 17, 2014, by the Ministry
of Environmental Protection and the Ministry of Land and Resources
of the People's Republic of China, indicates that 16.1% of the
surveyed land of 6.3 million square kilometers (about 65.6% of the
territorial area, covering all the arable land and part of the
forest land, the grassland and the construction land of China) is
contaminated, wherein 82.8% of the contaminated land is
contaminated by the heavy metals; and 19.4% of the arable land is
contaminated, mainly by the pollutants of cadmium (Cd), nickel,
copper, arsenic, mercury and plumbum (Pb), which means that nearly
one fifth of the arable land suffers from the heavy metal
contamination. In China, the soil heavy metal contamination leads
to a decrease of 10 million tons in the food production, and 12
million tons of food is contaminated by the heavy metals.
[0007] Unlike the organic pollutants, the non-degradable heavy
metals are unable to be remedied through a microbial degradation or
a chemical degradation. Thus, the soil heavy metal contamination is
accumulative and relatively stable, which leads to a relatively
difficult remediation of the soil contaminated by the heavy
metals.
[0008] Generally, the soil heavy metal remediation is divided into
the physical remediation, the bio-remediation and the chemical
remediation.
[0009] The physical remediation mainly comprises: agricultural
engineering measures (soil replacement and soil dressing), heat
treatment, vitrification and electrokinetic remediation. The
agricultural engineering measures are suitable for the small area
of the contaminated soil. However, because of involving digging and
moving soil, the agricultural engineering measures consume massive
manpower, material resources and financial resources; and the
replaced soil also needs to be treated. Thus, the agricultural
engineering measures have a high treatment cost; it is difficult to
treat a deep pollution by the agricultural engineering measures,
especially for a situation that the pollutants permeate into the
saturated layer soil and the underground water; and the
agricultural engineering measures destroy the original soil
structure and the ecological environment. The heat treatment has a
high energy consumption and a high operation cost, and is merely
suitable for volatile pollutants. The vitrification is expensive.
The vitrified soil still needs to be landfilled, which occupies
lands and wastes resources. The electrokinetic remediation is
merely suitable for the sandy soil and expensive.
[0010] The bio-remediation, through the metabolism of the organisms
(microorganisms, plants and animals), absorbs and removes the heavy
metals in the soil or transforms the heavy metals, so as to reduce
the toxicity and purify the soil. The microorganism remediation is
an emerging soil remediation method, but still in the research
phase because of a high cost and a difficult microbial strain
selection. The lower animals for remediating the soil are limited
in the number, and the lower animals after absorbing the heavy
metals may be released into the soil again to cause a secondary
pollution. The phytoremediation accumulates the heavy metals in the
soil by accumulators and hyperaccumulators, and the plants are
collected and centralized to detach the heavy metals from the
contaminated soil, so as to remove the heavy metals in the
contaminated soil. The phytoremediation is the most promising
original ecological soil treatment technology at present, but is
obviously disadvantageous as follows. Firstly, the
hyperaccumulators grow slowly and have a long remediation period,
generally 3-5 years; secondly, the phytoremediation is merely able
to accumulate one specific heavy metal or some specific heavy
metals, but the soil is generally contaminated by a combination of
the heavy metals; thirdly, the soil rich in the heavy metals
impairs the growth of the hyperaccumulators, leading to the low
heights, the low biomass, the slow growth and the long growth
period of the hyperaccumulators, so as to decrease the remediation
efficiency and the remediation rate; and fourthly, the
hyperaccumulators need to be harvested and properly disposed as
waste, otherwise may threaten the biodiversity to a certain
degree.
[0011] The chemical remediation comprises chemical washing
remediation and in-situ chemical immobilization remediation.
[0012] The chemical washing remediation washes the soil with
washing agents (surfactants, organic acids and salts thereof, and
chelating agents) to transfer the heavy metals from the soil to the
waste water, and then the waste water is recycled and treated, so
as to remedy the soil. However, the chemical washing remediation is
expensive; while removing the heavy metals, the chemical washing
remediation leads to a nutrient loss of the soil, and carries the
washing agents into the soil, becoming another contamination
resource. The chemical washing remediation destroys the soil
structure, contaminates the underground water, and leads to a high
environmental risk.
[0013] The in-situ chemical immobilization remediation is to add
chemical reagents or chemical materials into the soil. Through
absorption, precipitation, complexing, ion exchanging and a redox
reaction, the heavy metals are turned into insoluble substances
having a low solubility and a low dissolution rate, which reduces
the mobility of the heavy metals in the soil and the possibility to
be absorbed by the plants. Thus, usually the chemical materials are
also called amendments. The heavy metals are immobilized stably in
the soil through the amendments, so as to realize treating and
remediating the contaminated soil.
[0014] Compared with other remediation measures, the in-situ
chemical immobilization remediation of the soil with the amendments
has advantages of the wide application scope, the high processing
capacity, the fast yield, being economical and convenient, and
maintaining the inherent physical and chemical properties of the
soil unchanged. The in-situ chemical immobilization remediation is
considered as a potential alternative technology which is able to
reduce the health risk of the heavy metal environment, and thus has
a good application prospect.
[0015] The conventional amendments are mainly divided into the
inorganic amendments and the organic amendments. The inorganic
amendments mainly comprise minerals (sepiolite, bentonite,
montmorillonoid, zeolite powder, attapulgite, diatomite and
metallic oxide ores such as aluminum oxide ore, manganese oxide ore
and iron oxide ore), phosphates (phosphate, hydrophosphate and
sodium dihydrogen phosphate), alkaline substances (calcium oxide,
calcium hydroxide, carbonate and bicarbonate), sulfides
(polysulfide, hydrosulfide salt and sulfide) and biochars (straw
charcoal powder, rice husk charcoal powder and bamboo shell
charcoal powder). The organic amendments comprise humic acids,
organic fertilizers and chelating agents.
[0016] The published amendment is usually one of the conventional
amendments or a combination of at least two of the conventional
amendments. The Chinese patent application, CN 200910070713.4,
discloses a combined amendment comprising sepiolite and dicalcium
phosphate, which is able to immobilize the soil having a total Cd
content of 1.2 mg/Kg and an available Cd content of 0.6 mg/Kg. When
the addition dosage of the combined amendment reaches 9% of the
soil, the available Cd content is decreased to 0.23 mg/Kg by 61%.
The Chinese patent application, CN 201210227669.5, discloses a
combined amendment comprising slaked lime, monopotassium phosphate,
plant ash and silkworm excrement, for immobilizing and remedying
the soil containing Pb and Cd. When the addition dosage of the
combined amendment reaches 2% of the soil, the available Pb content
is decreased by 47.61% and the available Cd content is decreased by
50.57% after 30 days. The Chinese patent application, CN
201110203080.7, discloses a combined amendment comprising calcium
hydroxide, fly ash, sodium carbonate, polycrylamide and sodium
sulfate, for processing the soil with an in-situ immobilization
remediation. When the addition dosage of the combined amendment
reaches 5% of the soil, the leaching content of Pb, Zinc (Zn), Cd
and Copper (Cu) is respectively decreased from 2.86 mg/L, 1.37
mg/L, 0.31 mg/L and 4.65 mg/L to 0.35 mg/L, 0.42 mg/L, 0.03 mg/L,
0.42 mg/L and 0.84 mg/L. The Chinese patent application discloses a
combined amendment comprising humic acid mineral powder, calcium
magnesium phosphate fertilizer and quicklime. When the addition
dosage of the combined amendment reaches 3% of the soil, the
available Cd content in the soil is decreased from 8.90 mg/Kg to
7.38 mg/Kg. The Chinese patent application, CN 201210244674.7,
discloses a combined amendment comprising rice husk charcoal,
powdered straw and sifted fly ash. When the addition dosage of the
combined amendment reaches 8% of the soil, the available Pb content
in the soil is decreased by 73.25%.
[0017] The above conventional amendments have the following
limitations. Firstly, for the heavily contaminated soil, the
immobilization effect of the conventional amendments is negligible.
Secondly, the conventional amendments are unable to guarantee a
long-term and stable existence of the remedied soil in the nature.
When the environment changes, the immobilized heavy metals may be
activated and then be dissolved out again, causing a secondary
contamination.
[0018] Thus, it is urgent to provide a highly-efficient amendment
with an enhanced ability to stabilize the heavy metals with regard
to the research of the in-situ remediation amendment of the heavy
metals in the soil.
[0019] With the development of the polymers, based on the
conventional one-dimensional linear, two-dimensional crosslinked or
slightly branched polymers, the highly-branched polymers having a
three-dimensional spatial structure are developed. According to the
structure, the highly-branched polymers are divided into the
dendrimers and the hyperbranched polymers. The dendrimers have a
regular structure, but the hyperbranched polymers have an irregular
structure. In the 21.sup.st century, the highly-branched polymer
has attracted more and more attentions of the scientists around the
world, because of the special structure. The highly-branched
polymer has an important application prospect in the fields of
industry, agriculture, national defense, biomedical,
sustained-release materials and catalysis.
[0020] The present invention adopts a dithiocarbamate
functionalized dendrimer with an alkylenediamine core as a soil
heavy metal immobilization amendment, which has good performance in
stabilizing the heavy metals in the soil, has an ability to reduce
the available heavy metals and the carbonate bound forms of the
heavy metals and to well resist acid rain, and guarantees a
long-term stability of the remedied soil in the environment.
SUMMARY OF THE PRESENT INVENTION
[0021] An object of the present invention is to overcome the large
dosage and the poor stabilization of the conventional
immobilization amendments, and to provide a dithiocarbamate
functionalized dendrimer with an alkylenediamine core as a soil
heavy metal immobilization amendment and a preparation method
thereof. The soil heavy metal immobilization amendment of the
present invention has good stabilization performance for heavy
metals in soil and a strong resistance to acid and alkali, and
satisfies a long-term safety requirement of the soil.
[0022] Accordingly, in order to accomplish the above objects, the
present invention provides a soil heavy metal immobilization
amendment which is a dithiocarbamate functionalized dendrimer with
an alkylenediamine core.
[0023] The dithiocarbamate functionalized dendrimer with the
alkylenediamine core has a chemical formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2-
OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2(CH.sub.2).sub.bCH.sub.2N(CSSM).sub.2).s-
ub.2].sub.2}.sub.2; and
[0024] the dithiocarbamate functionalized dendrimer with the
alkylenediamine core has a structural formula of:
##STR00001##
[0025] wherein a is a positive integer larger than 2; b is a
positive integer at a range of 0-4; and M is Na.sup.+, NH4.sup.+ or
K.sup.+.
[0026] The present invention also provides a method for preparing
the dithiocarbamate functionalized dendrimer with the
alkylenediamine core as the soil heavy metal immobilization
amendment, comprising steps of:
[0027] (1) Preparing a double bond-terminated lower generation
dendrimer, comprising steps of:
[0028] Adding a methanol solution of trimethylolpropane triacrylate
(C.sub.2H.sub.5C(CH.sub.2OOCHC.dbd.CH.sub.2).sub.3, TMPTA for
short) into a first round-bottom flask with a first stirrer, a
first reflux condenser and a first thermometer; then dropping a
methanol solution of first alkylenediamine
(H.sub.2N(CH.sub.2).sub.aNH.sub.2, ADA for short) by two to five
times into the first round-bottom flask, at a temperature of lower
than 10.degree. C., under a nitrogen protection and a stirring
condition, wherein a is a positive integer larger than 2;
controlling a dropping speed to keep the temperature lower than
10.degree. C. when dropping; reacting for 8-16 h at a temperature
of 25.degree. C. after each dropping; reacting for 12-18 h at the
temperature of 25.degree. C. after all the first ADA is dropped;
filtering a pale amber product which is dissolved out after
reacting; washing the pale amber product with methanol; drying in a
vacuum at a temperature of 40.degree. C.; and obtaining a pale
amber double bond-terminated lower generation dendrimer (ADA/TMPTA
for short);
[0029] wherein the ADA/TMPTA has a chemical formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2-
OCOCH.sub.2.dbd.CH.sub.2).sub.2].sub.2}.sub.2; and
[0030] a reaction equation of the step (1) is:
##STR00002##
[0031] wherein a is the positive integer larger than 2;
[0032] (2) Preparing an amine-terminated higher generation
dendrimer, comprising steps of:
[0033] Adding an alcohol solution of second alkylenediamine
(H.sub.2NCH.sub.2(CH.sub.2).sub.bCH.sub.2NH.sub.2, ADA for short)
into a second round-bottom flask with a second stirrer, a second
reflux condenser and a second thermometer, wherein b is a positive
integer at a range of 0-4; adding the ADA/TMPTA obtained by the
step (1) to the second round-bottom flask, and then stirring and
uniformly mixing, at the temperature of lower than 10.degree. C.,
under the nitrogen protection and the stirring condition; reacting
for 20-30 h at the temperature of 25.degree. C.; distilling under a
reduced pressure for 3-5 h at a temperature of 80-100.degree. C. to
remove the methanol and redundant ethylenediamine (EDA for short);
and obtaining a pale amber viscous product which is the
amine-terminated higher generation dendrimer (ADA/TMPTA/ADA for
short);
[0034] wherein the ADA/TMPTA/ADA has a chemical formula of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2-
OCOCH.sub.2CH.sub.2NHCH.sub.2(CH.sub.2).sub.bCH.sub.2NH.sub.2).sub.2].sub.-
2}.sub.2; and
[0035] a reaction equation of the step (2) is:
##STR00003##
[0036] wherein a is the positive integer larger than 2 and b is the
positive integer at the range of 0-4; and
[0037] (3) Preparing a dithiocarbamate functionalized dendrimer
with an alkylenediamine core, comprising steps of:
[0038] Adding an alcohol solution of the ADA/TMPTA/ADA obtained by
the step (2) into a third round-bottom flask with a third stirrer,
a third reflux condenser and a third thermometer; decreasing the
temperature to be lower than 10.degree. C., and introducing
nitrogen; dropping an alkali solution slowly into the third
round-bottom flask at the temperature of lower than 10.degree. C.,
and then dropping an ethanol solution of carbon disulfide at the
temperature of lower than 10.degree. C., so as to form an aqueous
reaction mixture; reacting, by the aqueous reaction mixture, for
2-5 h at a temperature of 5-10.degree. C. after dropping;
increasing the temperature to 25.degree. C., and then continuing
reacting, by the aqueous reaction mixture, for 3-5 h; storing the
aqueous reaction mixture overnight to dissolve out white
precipitate; filtering out the precipitate and washing the
precipitate with a small amount of ethanol; and then filtering
again to obtain a target product: the dithiocarbamate
functionalized dendrimer with the alkylenediamine core
(ADA/TMPTA/ADA-24CSSNa for short);
[0039] wherein the ADA/TMPTA/ADA-24CSSNa has a chemical formula
of:
(CH.sub.2).sub.a{N[CH.sub.2CH.sub.2COOCH.sub.2C(C.sub.2H.sub.5)(CH.sub.2-
OCOCH.sub.2CH.sub.2N(CSSM)CH.sub.2(CH.sub.2).sub.bCH.sub.2N(CSSM).sub.2).s-
ub.2].sub.2}.sub.2; and
[0040] a reaction equation of the step (3) is:
##STR00004##
[0041] wherein a is the positive integer larger than 2, b is the
positive integer at the range of 0-4, and M is Na.sup.+,
NH.sub.4.sup.+ or K.sup.+.
[0042] In the step (1), a mole ratio of the TMPTA to the first ADA
is 4.1:1-4.9:1; in the step (2), a mole ratio of the ADA/TMPTA to
the second ADA is 1:15-1:20; and in the step (3), a mole ratio
among the ADA/TMPTA/ADA, the carbon disulfide and the alkali is
1:(30-36):(30-36).
[0043] According to the present invention, the TMPTA, the ADA and
the carbon disulfide are all commercially available.
[0044] According to the present invention, the alkali is sodium
hydroxide, potassium hydroxide or ammonia, wherein the sodium
hydroxide, the potassium hydroxide and the ammonia are all
commercially available.
[0045] During the research, inventors of the present invention find
that: when the TMPTA and the first ADA are mixed according to the
mole ratio of 4.1:1-4.9:1, it is possible to theoretically obtain a
double bond-terminated polymer with the alkylenediamine core;
however, an adding order and an adding method of the raw materials
determine a purity and a yield of the product. For example, Chunhua
Ning prepared a double bond-terminated lower generation dendrimer,
wherein a and b were both 2 (Dendrimer synthesis with raw materials
of EDA and TMPTA, 1.sup.st series of Engineering Technology of
China Doctor/Master Dissertations Full-text Database, 2.sup.nd
issue in 2004, B014-14, p 18). The method of Chunhua Ning included
steps of: respectively adding the methanol, the TMPTA and the EDA
into a three-necked bottle; and stirring for 6-28 h at a
temperature of 30-40.degree. C. However, when a mole ratio of the
TMPTA to the EDA was 4.71:1, 4.44:1 and 4:1, and when the reaction
time was respectively 3.5 h, 2.5 h and 0.5 h, the aqueous reaction
mixture was solidified and failed to continue reacting. When the
mole ratio of the TMPTA to the EDA was 5.33:1-8.00:1, it is failed
to obtain a product. The conclusion was drawn from the thesis of
Chunhua Ning that a product having an ideal purity is merely
obtained at a temperature of 30.degree. C. when the mole ratio of
the TMPTA to the EDA is 5.00:1 and the reaction time is 6 h,
wherein the yield was 65.11%.
[0046] During the research, the inventors of the present invention
also find that: when the TMPTA and the EDA is simultaneously added
according to a stoichiometric ratio of 4:1, the aqueous reaction
mixture is solidified in merely half an hour; and, when the mole
ratio of the EDA to the TMPTA increases from 1:4.0 to 1:4.9, a time
to solidify gradually increases. The reason is that excessive TMPTA
prevents other two double bonds of the same TMPTA from reacting
with a primary amine group of the EDA molecule, which avoids a
chain reaction to form a bridge structure and accordingly avoids
the aqueous reaction mixture being solidified. When the mole ratio
of the EDA to the TMPTA is 1:6.0, although the aqueous reaction
mixture is not solidified, a product yield is low. The inventors of
the present invention find that: when the adding order is changed
to firstly add the TMPTA and then add the EDA by several times,
since the TMPTA is excessive all the time, it is guaranteed that
the TMPTA react with the EDA according to the mole ratio of 4:1, so
as to prevent the other double bond of the TMPTA from reacting with
other EDA to form the bridge structure and accordingly avoid the
aqueous reaction mixture being solidified. When the TMPTA and the
EDA is added according to the stoichiometric ratio of 4:1, the
product yield is 79.91%. When the mole ratio of the TMPTA to the
EDA increases from 4.1:1 to 4.9:1, the product yield gradually
increases; when the mole ratio of the TMPTA to the EDA increases
from 5.0:1 to 5.4:1, the product yield gradually decreases; and,
when the mole ratio of the TMPTA to the EDA is larger than 5.5:1,
it is failed to obtain the product with a normal processing method.
The reason is that the product is insoluble in the methanol, but
soluble in the TMPTA, and thus the product is unable to dissolve
out from a mixed liquid of the excessive TMPTA and the methanol.
Thus, the mole ratio of the TMPTA to the EDA is preferably lower
than 5.0:1, namely the mole ratio of the TMPTA to the ADA is 4.1:1
to 4.9:1. The inventors of the present invention further find in
the research that: when the first ADA
(H.sub.2N(CH.sub.2).sub.aNH.sub.2, a>2), such as propanediamine
and butanediamine, serves as the core, a yield of accordingly
obtained double bond-terminated lower generation dendrimer is
higher than the yield of obtained double bond-terminated lower
generation dendrimer with an ethylenediamine core, because of
avoiding a steric hindrance of a reaction between four TMPTA
molecules and an ADA molecule. The inventors of the present
invention further find that: with an increase of a reaction
temperature, an appearance color of the product is deepened and the
product yield is slightly decreased. The reason may be that the
increase of the reaction temperature leads to an oxidation of the
amine group and accordingly a decrease in purity. Thus, preferably,
the reaction temperature is 25.degree. C.
[0047] In the steps of preparing the double bond-terminated lower
generation dendrimer of the present invention, the first ADA
(H.sub.2N(CH.sub.2).sub.aNH.sub.2, a>2) serves as the core; the
TMPTA is firstly added and then the first ADA is added by several
times; and the mole ratio of the TMPTA to the first ADA is
4.1:1-4.9:1.
[0048] The present invention further provides a method for in-suit
immobilizing and remedying soil contaminated by heavy metals,
comprising steps of: preparing the dithiocarbamate functionalized
dendrimer with the alkylenediamine core into a solution; uniformly
mixing the solution with the soil contaminated by the heavy metals,
wherein an addition dosage of the solution is 0.5%-5% of a weight
of the soil; and storing the mixed soil for at least one day, so as
to realize a quick in-situ immobilization for the soil contaminated
by the heavy metals, and to resist an influence from natural
environment for a long term (such as acid rain).
[0049] The dendrimer provided by the present invention is a
functionalized dendrimer with the alkylenediamine core, a
dithiocarbamate pendant functional group and a dithiocarbamate end
functional group. According to experiments, the dithiocarbamate
functionalized dendrimer with the alkylenediamine core is able to
effectively immobilize the heavy metals in the soil, because of a
special highly-branched structure thereof. Compared with the
conventional immobilization amendments in the market, the
dithiocarbamate functionalized dendrimer with the alkylenediamine
core of the present invention has a low addition dosage and a good
resistance to acid rain while immobilizing the heavy metals, and
guarantees a long-term safety of the remedied soil.
[0050] The dithiocarbamate functionalized dendrimer with the
alkylenediamine core, provided by the present invention, is able to
serve as the in-suit immobilization amendment for the soil
contaminated by the heavy metals, and is also applicable to
stabilize the heavy metals in fly ashes of waste incineration and
treat waste water containing the heavy metals.
[0051] These and other objectives, features, and advantages of the
present invention will become apparent from the following detailed
description, the accompanying drawings, and the appended
claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0052] One skilled in the art will understand that the embodiment
of the present invention as shown in the drawings and described
above is exemplary only and not intended to be limiting.
[0053] It will thus be seen that the objects of the present
invention have been fully and effectively accomplished. Its
embodiments have been shown and described for the purposes of
illustrating the functional and structural principles of the
present invention and is subject to change without departure from
such principles. Therefore, this invention includes all
modifications encompassed within the spirit and scope of the
following claims.
[0054] Stabilizers as comparisons 1-2 are both commercially
available.
[0055] Comparison 1: inorganic stabilizer, sodium sulfide
(Na.sub.2S)
[0056] Comparison 2: organic stabilizer, thiourea
(H.sub.2NCSNH.sub.2)
Example 1
Preparation of Dithiocarbamate Functionalized Dendrimer with
Butanediamine Core (a=4, b=2)
[0057] (1) Preparation of Double Bond-Terminated Lower Generation
Dendrimer
[0058] 266.40 g (50.00%, 0.45 mol) of a methanol solution of
trimethylolpropane triacrylate (TMPTA for short) was added into a
first round-bottom flask with a first stirrer, a first reflux
condenser and a first thermometer. 8.80 g (50.00%, 0.05 mol) of a
methanol solution of butanediamine (1,4-Butanediamine, BDA for
short) was dropped into the first round-bottom flask to form a
first mixture at a temperature of lower than 10.degree. C., under a
nitrogen protection and a stirring condition, wherein a dropping
speed was controlled to keep the temperature lower than 10.degree.
C. when dropping. The temperature was increased to 25.degree. C.;
then, the first mixture reacted for 10 h. Thereafter, the
temperature was decreased to 10.degree. C., and 8.80 g (50.00%,
0.05 mol) of the methanol solution of BDA was added again into the
first round-bottom flask to form a second mixture, wherein the
dropping speed was controlled to keep the temperature lower than
10.degree. C. when dropping. Thereafter, the temperature was
increased to 25.degree. C. and the second mixture reacted for 16 h.
After the reaction was finished, a first pale amber viscous product
was dissolved out. The first pale amber viscous product was
filtered out, washed with ethanol, and dried in a vacuum at a
temperature of 40.degree. C. Then, a pale amber product of 120.86 g
was obtained, namely a double bond-terminated lower generation
dendrimer (BDA/TMPTA for short) with a yield of 95.02%.
[0059] (2) Preparation of Amine-Terminated Higher Generation
Dendrimer
[0060] 96.00 g (50.00%, 0.80 mol) of an ethanol solution of
ethylenediamine (EDA for short) was added into a second
round-bottom flask with a second stirrer, a second reflux condenser
and a second thermometer. 127.20 g (50.00%, 0.05 mol) BDA/TMPTA
obtained by the step (1) was added into the second round-bottom
flask to form a third mixture at the temperature of lower than
10.degree. C. under the nitrogen protection and the stirring
condition, stirred and uniformly mixed. Thereafter, the third
mixture reacted for 24 h at the temperature of 25.degree. C. Then,
the third mixture was distilled under a reduced pressure for 5 h at
a temperature of 85.degree. C. to remove ethanol and excessive EDA,
so as to obtain a second pale amber viscous product of 86.05 g,
namely an amine-terminated higher generation dendrimer
(BDA/TMPTA/EDA) with a yield of 98.23%.
[0061] (3) Preparation of Dithiocarbamate Functionalized Dendrimer
with Butanediamine Core
[0062] 87.60 g (50.00%, 0.025 mol) of an ethanol solution of the
BDA/TMPTA/EDA obtained by the step (2) was added into a third
round-bottom flask with a third stirrer, a third reflux condenser
and a third thermometer. The temperature was decreased to be lower
than 10.degree. C. and nitrogen was introduced. At the temperature
of lower than 10.degree. C., 60.00 g (50.00%, 0.75 mol) of a sodium
hydroxide solution was slowly dropped to the third round-bottom
flask, and then 121.60 g (50.00%, 0.80 mol) of an ethanol solution
of carbon disulfide was dropped to the third round-bottom flask, so
as to form a fourth mixture, wherein the temperature was controlled
to be lower than 10.degree. C. when dropping. After dropping is
finished, the fourth mixture reacted for 4 h at the temperature of
10.degree. C. Thereafter, the temperature was increased to
25.degree. C. and the fourth mixture continued to react for 5 h.
The fourth mixture, as an aqueous reaction mixture, was stored
overnight to dissolve out white precipitate. The white precipitate
was filtered out, washed with a small amount of the ethanol, and
then filtered out again. Thereafter, a product of 96.65 g was
obtained, namely a dithiocarbamate functionalized dendrimer with a
butanediamine core (BDA/TMPTA/EDA-24CSSNa) with a yield of
94.20%.
[0063] A nuclear magnetic resonance .sup.13C NMR (D.sub.2O)
spectrum of the obtained star-shaped hyperbranched polymer is: 8.56
ppm, 21.25 ppm, 27.16 ppm, 32.37 ppm, 33.65 ppm, 36.15 ppm, 48.26
ppm, 49.92 ppm, 50.36 ppm, 54.26 ppm, 55.39 ppm, 65.87 ppm, 66.21
ppm, 176.68 ppm, 177.11 ppm, 207.24 ppm and 210.15 ppm. A structure
of the BDA/TMPTA/EDA-24CSSNa is:
##STR00005##
Example 2
Preparation of Dithiocarbamate Functionalized Dendrimer with
Hexanediamine Core (a=6, b=4)
[0064] (1) Preparation of Double Bond-Terminated Lower Generation
Dendrimer
[0065] 266.40 g (50.00%, 0.45 mol) of a methanol solution of
trimethylolpropane triacrylate (TMPTA for short) was added into a
first round-bottom flask with a first stirrer, a first reflux
condenser and a first thermometer. 11.60 g (50.00%, 0.05 mol) of a
methanol solution of hexanediamine (1,6-Hexanediamine, HDA for
short) was dropped into the first round-bottom flask to form a
first mixture, at a temperature of lower than 10.degree. C., under
a nitrogen protection and a stirring condition, wherein a dropping
speed was controlled to keep the temperature lower than 10.degree.
C. when dropping. The temperature was increased to 25.degree. C.
and the first mixture reacted for 10 h. Thereafter, the temperature
was decreased to 10.degree. C., and 11.60 g (50.00%, 0.05 mol) of
the methanol solution of HDA was dropped into the first
round-bottom flask to form a second mixture, wherein the dropping
speed was controlled to keep the temperature lower than 10.degree.
C. when dropping. Thereafter, the temperature was increased to
25.degree. C. and the second mixture reacted for 16 h. After the
reaction of the second mixture was finished, a first pale amber
viscous product was dissolved out. The first pale amber viscous
product was filtered out, washed with methanol, and dried in a
vacuum at a temperature of 40.degree. C., so as to obtain a pale
amber product of 122.85 g, namely a double bond-terminated lower
generation dendrimer (HDA/TMPTA for short) with a yield of
94.50%.
[0066] (2) Preparation of Amine-Terminated Higher Generation
Dendrimer
[0067] 140.80 g (50.00%, 0.80 mol) of a methanol solution of
butanediamine (BDA for short) was added into a second round-bottom
flask with a second stirrer, a second reflux condenser and a second
thermometer. 130.00 g (50.00%, 0.05 mol) HDA/TMPTA obtained by the
step (1) was added into the second round-bottom flask to form a
third mixture, at the temperature of lower than 10.degree. C.,
under the nitrogen protection and the stirring condition. After
being stirred and uniformly mixed, the third mixture reacted for 24
h at the temperature of 25.degree. C. Then, the third mixture was
distilled under a reduced pressure for 5 h at a temperature of
95.degree. C. to remove methanol and excessive BDA, so as to obtain
a second pale amber viscous product of 98.21 g, namely an
amine-terminated higher generation dendrimer (HDA/TMPTA/BDA) with a
yield of 98.01%.
[0068] (3) Preparation of Dithiocarbamate Functionalized Dendrimer
with Hexanediamine Core
[0069] 100.20 g (50.00%, 0.025 mol) of a methanol solution of
HDA/TMPTA/BDA obtained by the step (2) was added into a third
round-bottom flask with a third stirrer, a third reflux condenser
and a third thermometer. The temperature was decreased to be lower
than 10.degree. C. and nitrogen was introduced. At the temperature
of lower than 10.degree. C., 64.00 g (50.00%, 0.80 mol) of a sodium
hydroxide solution was slowly dropped into the third round-bottom
flask, and then 121.60 g (50.00%, 0.80 mol) of an ethanol solution
of carbon disulfide was dropped into the third round-bottom flask,
so as to form a fourth mixture, wherein the temperature was
controlled to be lower than 10.degree. C. when dropping. After
dropping is finished, the fourth mixture reacted for 4 h at the
temperature of 8.degree. C. Then the temperature was increased to
25.degree. C. and the fourth mixture continued to react for 5 h.
Then, the fourth mixture, as an aqueous reaction mixture, was
stored overnight to dissolve out white precipitate. The white
precipitate was filtered out, washed with a small amount of
ethanol, and then filtered again, so as to obtain a product of
101.28 g, namely a dithiocarbamate functionalized dendrimer with a
hexanediamine core (HDA/TMPTA/BDA-24CSSNa) with a yield of
93.00%.
[0070] A nuclear magnetic resonance .sup.13C NMR (D.sub.2O)
spectrum of the obtained star-shaped hyperbranched polymer is: 8.94
ppm, 21.02 ppm, 24.01 ppm, 24.89 ppm, 28.23 ppm, 20.18 ppm, 33.77
ppm, 33.95 ppm, 36.12 ppm, 47.68 ppm, 48.09 ppm, 51.02 ppm, 51.83
ppm, 55.41 ppm, 67.27 ppm, 68.75 ppm, 176.31 ppm, 176.69 ppm,
205.11 ppm and 209.64 ppm. A structure of the HDA/TMPTA/BDA-24CSSNa
is:
##STR00006##
Example 3
Application
[0071] Tested soil is contaminated by Cd and Pb, and basic physical
and chemical properties of the tested soil are showed in Table 1.
The dithiocarbamate functionalized dendrimers with the
alkylenediamine core as the amendments, obtained by the examples 1
and 2, and the sodium sulfide and the thiourea of the comparisons 1
and 2 were added based on a mass percentage of the soil. Then
water, with the same weight as the amendments, was added, and the
soil was uniformly mixed. The uniformly mixed soil was dried
naturally at a room temperature, so as to obtain immobilized and
remedied soil.
TABLE-US-00001 TABLE 1 Basic physical and chemical properties of
tested soil pH Water content (%) Plumbum (mg/Kg) Cadmium (mg/Kg)
7.37 2.03 1623.389 31.267
[0072] The soil was tested through an extraction method defined in
Solid waste-Extraction procedure for leaching toxicity-Acetic acid
buffer solution (HJ/T300-2007) to measure a heavy metal content in
a leaching liquid. Experimental results are showed in Table 2.
[0073] The dithiocarbamate functionalized dendrimer with the
alkylenediamine core of the present invention has obviously better
immobilization performance for the heavy metals in the soil than
conventional amendments, i.e., sodium sulfide and thiourea. For
example, when an addition dosage reached 2% of the soil, a leaching
value of Cd and Pb of the soil remedied by the amendment of the
present invention satisfies concentration requirements of class
III, defined in Quality standard for ground water (GB/T 14848-93);
and, when the addition dosage reached 3% of the soil, the leaching
value of Cd and Pb of the soil remedied by the amendment of the
present invention satisfies the concentration requirements of class
II, defined in the Quality standard for ground water (GB/T
14848-93).
[0074] When the addition dosage of the thiourea reached 15% of the
soil, the leaching value of Cd and Pb of the remedied soil
satisfies the concentration requirements of the class IV, defined
in Quality standard for ground water (GB/T 14848-93).
[0075] When the addition dosage of the sodium sulfide reached 15%
of the soil, the leaching value of Cd and Pb of the remedied soil
is unable to satisfy the concentration requirements of the class
IV, defined in Quality standard for ground water (GB/T
14848-93).
[0076] Thus, compared with the conventional amendments sodium
sulfide and thiourea, the dithiocarbamate functionalized dendrimer
with the alkylenediamine core of the present invention has
highly-efficient immobilization performance for the heavy
metals.
TABLE-US-00002 TABLE 2 Leaching analysis of heavy metals of
immobilized and remedied soil Cd Pb leaching leaching concen-
concen- Dosage tration tration Order Stabilizer (%) (mg/L) (mg/L)
Original -- 0.895 14.836 soil Example 1 BDA/TMPTA/EDA- 0.5 0.238
4.236 24CSSNa 1.0 0.162 0.981 2.0 0.001 0.042 3.0 0 0.011 Example 2
HDA/TMPTA/BDA- 0.5 0.227 4.192 24CSSNa 1.0 0.158 0.898 2.0 0 0.034
3.0 0 0.012 Comparison 1 sodium sulfide 3.0 0.658 11.036 5.0 0.515
7.357 10.0 0.428 3.016 15.0 0.297 1.128 Comparison 2 thiourea 3.0
0.602 8.123 5.0 0.359 2.108 10.0 0.219 0.232 15.0 0.009 0.058
Concentration requirements defined Class II 0.001 0.02 in Quality
standard for ground water Class III 0.01 0.05 (GB/T 14848-93) Class
IV 0.01 0.1
[0077] Existing forms of Pb and Cd in the soil were analyzed
through a TESSIER method (Tessier A., Campbell P. G. C., Bisson M.
Sequential Extraction Procedure for the Speciation of Particulate
Trace Metals [J]. Analytical Chemistry, 1979, 7(51): 844-850), and
experimental results thereof are showed in Table 3 and Table 4.
TABLE-US-00003 TABLE 3 Analysis for existing forms of Cd in soil
Existing forms of heavy metals (mg/kg) Dosage Carbonate Fe--Mn
Organic Order (%) Exchangeable bound oxidation bound Residual Total
Original 0 3.233 20.230 4.675 2.087 1.042 31.267 soil Example 1 0.5
0 4.598 20.529 5.652 1.128 31.907 1 0 2.353 12.339 15.282 2.328
32.302 2 0 0 11.383 19.509 3.021 33.913 3 0 0 6.339 17.893 6.926
31.158 Example 2 0.5 0 4.423 21.347 5.298 1.176 32.244 1 0 2.098
13.418 14.035 1.981 31.532 2 0 0 10.116 18.371 3.927 32.414 3 0 0
5.916 16.289 8.642 30.847 Comparison 1 3 2.086 21.615 4.455 2.161
0.942 31.259 5 0.509 15.694 10.519 2.744 1.007 30.473 10 0.206
10.225 17.855 3.209 1.103 32.598 15 0.358 4.627 22.117 4.172 1.011
32.285 Comparison 2 3 0.825 19.982 5.216 1.985 1.079 29.087 5 0.012
17.237 9.015 2.689 1.102 30.044 10 0 7.248 18.896 4.009 1.282
31.435 15 0 2.001 23.349 5.937 1.198 32.485
TABLE-US-00004 TABLE 4 Analysis for existing forms of Pb in soil
Existing forms of heavy metals (mg/kg) Dosage Carbonate Fe--Mn
Organic Order (%) Exchangeable bound oxidation bound Residual Total
Original 0 57.883 806.545 420.158 302.406 36.397 1623.389 soil
Example 1 0.5 3.092 559.469 452.638 541.625 97.681 1654.505 1 0
213.328 467.822 782.261 165.223 1628.634 2 0 79.813 377.562 819.711
344.948 1622.034 3 0 11.252 263.699 787.538 624.972 1687.461
Example 2 0.5 3.298 556.669 450.183 592.242 73.284 1675.676 1 0
228.902 476.198 773.923 145.232 1624.255 2 0 81.292 369.155 820.119
354.458 1624.024 3 0 11.252 263.699 787.518 664.872 1727.341
Comparison 1 3 40.921 822.834 449.039 304.495 36.839 1654.128 5
22.297 834.626 424.905 310.395 35.396 1627.619 10 7.296 682.277
580.592 312.881 42.315 1625.361 15 2.895 372.669 796.723 478.099
52.676 1673.062 Comparison 2 3 23.043 839.486 423.672 301.153
37.388 1624.742 5 8.223 777.747 487.879 372.359 46.025 1692.233 10
1.098 327.664 784.136 475.915 57.023 1645.836 15 0 117.808 953.943
498.517 57.142 1627.41
[0078] According to the Table 3, when the addition dosage of the
amendment of the present invention reached 0.5% of the soil
(illustrated with the example 1), the exchangeable forms of Cd were
completely immobilized; the carbonate bound forms of Cd were
decreased from 20.230 mg/Kg to 4.598 mg/Kg; the Fe--Mn oxidation
and the organic bound forms of Cd were respectively increased from
4.675 mg/Kg and 2.087 mg/Kg to 20.529 mg/Kg and 5.652 mg/Kg; and
the residual forms of Cd were stable. That is to say, the
exchangeable and a portion of the carbonate bound forms of Cd were
changed into the more stable Fe--Mn oxidation and organic bound
forms of Cd. When the addition dosage of the amendment of the
present invention reached 2% of the soil, the exchangeable and the
carbonated bound forms of Cd were completely immobilized; and, the
Fe--Mn oxidation, the organic bound and the residual forms of Cd
were all increased. That is to say, all of the exchangeable and the
carbonated bound forms of Cd were changed into the more stable
Fe--Mn oxidation, organic bound and residual forms of Cd. The
sodium sulfide was merely able to partially decrease the
exchangeable and carbonate bound forms of Cd ions; and when the
addition dosage of the thiourea reached 10% of the soil, the
exchangeable and a portion of the carbonated bound forms of the Cd
ions were decreased.
[0079] According to the Table 4, when the addition dosage of the
amendment of the present invention reached 1% of the soil
(illustrated with the example 1), the exchangeable forms of Pb were
completely immobilized; the carbonate bound forms of Pb were
decreased from 806.545 mg/Kg to 213.328 mg/Kg; the Fe--Mn
oxidation, the organic bound and the residual forms of Pb were all
slightly increased. That is to say, the exchangeable and a portion
of the carbonated bound forms of Pb were changed into the more
stable Fe--Mn oxidation, organic bound and residual forms of Pb.
When the addition dosage of the amendment of the present invention
reached 3% of the soil, the carbonate bound forms of Pb were
decreased to 5.259 mg/Kg; and the Fe--Mn oxidation forms of Pb were
decreased from 420.158 mg/Kg to 263.669 mg/Kg. That is to say, all
of the exchangeable, 99.34% of the carbonated bound and 37.25% of
the Fe--Mn oxidation forms of Pb were changed into the more stable
organic bound and residual forms of Pb. The sodium sulfide was
merely able to partially decrease the exchangeable and the
carbonate bound forms of Pb ions; and when the addition dosage of
the thiourea reached 15% of the soil, the exchangeable and a
portion of the carbonate bound forms of the Pb ions were
decreased.
[0080] Bio-availability of the heavy metals in the soil is closely
related to chemical forms of the heavy metals. The exchangeable
forms of heavy metal ions, which plants are able to directly absorb
and utilize, belong to direct available forms of the heavy metal
ions (available forms of the heavy metal ions). The carbonate
bound, the Fe--Mn oxidation, the organic bound and the residual
forms of the heavy metal ions need to be changed into the
exchangeable forms of the heavy metal irons respectively under an
acidic condition, a deoxidization condition, an oxidation condition
and a strong oxidation condition, before being absorbed by the
plants. It is almost impossible for the soil in a natural world to
be exposed to the deoxidization environment, the oxidation
environment and the strong oxidation environment, but possible for
the soil in the natural world to be exposed to an acid rain
environment. Thus, the carbonate bound forms of the heavy metal
irons are able to be changed into the exchangeable forms of the
heavy metal ions under the acid rain and thus belong to potential
exchangeable forms of the heavy metal ions.
[0081] The dithiocarbamate functionalized dendrimer with the
alkylenediamine core, provided by the present invention, is able to
effectively immobilize the exchangeable forms of Cd and Pb and the
carbonated bound forms of Cd and Pb, with a low addition dosage, to
avoid a possibility that the heavy metals of the remedied soil are
dissolved out again under the acid rain condition and guarantee a
long-term safety of the soil.
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